Conversion of hydrocarbon oils



Patented Oct. i3, 1942 UNITED STATI-:s PATENT 4ovl-"FICE- coNvEasIoN oFnynRocAanoN oILs Charles L. Thomas, Chicago, Ill., assigner to UniversalOil Products Company, Chicago, Ill.`, a

corporation of Delaware Application August 25, 1939, Serial No, 291,8895 claims. (o1. 19e- 52) This invention relates tov-the conversion ofcrude petroleum into substantial yields of motor fuel products and is acontinuation-in-part of my co-pending application Serial No. 166,570,led September 30, 1937.4 The process mayalso be applied to similarhydrocarbon distillates from other sources, such as shale oils, coaltars, etc. f

More specically, the invention is concerned with a process involvingvboth thermal and catah lytic cracking with a denite interrelation ofsteps sothat maximum benefits are obtained not only in respect to yieldsand antiknock value of the finished product, but also in respect to thelife of the catalytic masses employed in the catalytic cracking step. Y

The limitations of ordinary non-catalytic cracking in the production ofhigh yields of antiknock gasoline are vfairly well recognized. Theincreasingly severe conditions of temperature,

pressure and time result in increased ant'iknock value of the gasolineproduct up to a certain point after which there is a disproportionatelylarge loss as gas and residue, so that the overall economics of such anoperation reaches a more or less definite limit. In order to increasethe antiknock value for a given yield ofV gasoline various catalyticmasses have been used with some success. y

Such catalytic masses have not been univer.- sally applicable to alltypes of hydrocarbon oils, particularly heavier fractions such as toppedcrude oil, reduced crude oil, etc. These masses have, however, been usedsuccessfully for processing distillate fractions of crude petroleum, andparticularly such fractions as may be distilled under ordinaryconditions of pressure without' substantial decomposition, such as gasoils, kerosene, and the like.

During thev catalytic cracking oi petroleum fractions, carbonaceousmaterials deposit on the catalytic surfaces necessitating frequentregener- In one specific embodiment the present invention comprises aprocess for converting crude hydrocarbon oil into substantial yields ofhigh octane number gasoline, which comprises charging said crudehydrocarbon oil to a primary fractionator, subjecting theheavyunvaporized portion of, the oil to non-.catalytic cracking in a tubularheating element followed by a reaction chamber operated at elevatedtemperatures and pressures to bring about substantial conversion togasoline and gas, separating and recoverilg the heavier products fromthis step-which are unsuit- A.able for further conversion, fractionatingthe remaining products in the aforesaid primary fractionator to producedxed gases, gasoline, and

an intermediate distillate fraction, contacting said intermediatefraction' in vaporous form with a cracking catalyst under conditionsadequate to A effect substantial cracking thereof, recovering the v, adiagrammatic outline of interconnected units in which the process may.be conducted. The

apparatus has not been drawn to scale, nor has any attempt been made toproportionate the various units thereof. Furthermore,`it has been ationby means of an oxygen-containing gas.

When heavier fractions such as topped crude oils, and the like, arecracked the amount ofV such carbonaceous deposits becomesdisproportionately large, and as a result reactivation becomes dimcultbecause of the amount of carbon which must be consumed, For this reasonthe chargingl stocks used in catalytic cracking are limited more or lessto distillate fractions. The present process, the character lof whichwill be developed in suc,

ceeding paragraphs, is a novel contribution to practiced methods ofcracking for increased yields and antiknock value by the combination ofcatalytic and non-catalytic cracking operations.

simpliiiedby leaving out various heat exchangers, condensers,stabilizers, and other parts of equipment which would be necessary inthe operation of the process but are not special features of theinvention. i The invention should not be construed as being limited tothe exact apparatus or conditions given therein. I

The charging stocks used in thisprocess may comprise distillatefractions of crude petroleum' oils, crude oils themselves, or toppedcrude oils,

' or similar hydrocarbon oils from other sources.

Referring tothe drawing, the crude petroleum oil is chargd'through lineI, valve 2, pump 3, valve ll,- into th lower section of fractionator 5wherein the lower boiling fractions arevaporized.

The unvaporized oil-is removed through line 6, I

valve l, pump 8 and valve S'into heating coil I0 which disposed infurnace'vl The temperaverted oil fmal or thecatalytic cracking..Aecordingtoarurther otline42,valv e of the oil is raised to a suitablecracking .-uquiu, products. Residum ou unam-.able for further conversionin the process is withdrawn through line I8 and valve I9 to storage. Theoverhead products pass thro h line 20 and valve 2 I to fractionator 5wherein the lower boiling materials are vaporized. The gasoline and gasare withdrawn through line v22 and valve 25 to suitable stabilizers heatexchangers, coolers, etc., not

shown.

An intermediate distillate fraction is withdrawn through line 24, valve25, pump 26 and valve 21 andpassed to coil 25 which is disposed infurnace 25. The iractionis heated to a desired conversion. A throughline 30 and valve 2i in vaporous form into catalytic converter l2.wherein a suitable cracking catalyst is disposed. The catalytic'converter may comprise any suitable form `such as bundles of tubescontaining the catalyst. reaction .The converters are usually usedinpairathetwoconvertersbeingelternatedbetween conversion andreactivationsteps. Thereaction products leave the catalytic converterthrough linen and valve and enter' fractionator Il. Gas and gasoline arewithdrawn through line 55 and valve changers, stabilizers, condensers.receiv reto.. not `shown. A portion of the insuiiieiently conmay bewithdrawn through line I and valve I5. A portion of the insuillcientlyoonverted oil may be passed through line 4l, valve 4I','line 40' andvalve 45" to line 55 andthence to flash chamber I1. Alternatively. theoil may be passed through line 4I" and valve 42"' toline I and thence tothe, fractionator. One or more intermediate fractionsmay be lwithdrawnfrom fractlonator I5 in a manner about to be described. A portion orverted fraction may be withdrawn through line I5, line 4l, valve 4I,line 42, valve 42,' pump 44, valve 45, line 55, valve 5I and line 24 tobe returned to the catalytic cracking step.

Alternatively a portion of the oil may be passed through line 45, valve45 and line I to iractionator 5. An intermediate fraction may betemperatureandpassed aaaaisi within the range of 850 1000 F.

to' the catalytic cracking step as may 31 through heatexsuperatmospheric up to all of the insuiliciently conwithdrawn throughune' iz and valve n which joins with line 4 2 and passed to either thetherstep as, just dethe heavy oil from lines Il scribed. A portion ofwith the fraction from line argini rnaybemixed 5 Inafurther alternativea side cut may be wlthdrawn through line 54, valve 55, pump 55. valve v51andvalve55toilashchamber I1,oraportion or all of theoil'may bepassedthroughline 5l, valve 5l andline I totherractionator. oithefractionmaybethroughlinell passed laliivllve52 whichjoinswitliline24,andthus crackingalternative a heavy from rractionator I5 returnedtothecatalytic v51,line valve 5I, line 24. pump 26, valve 21, coil 18, line 3|! and valve3|. Simultaneously a lighten fraction of insuiliciently converted oilmay be withdrawn through line54, valve 55, pump 56, valve 51, valve 58and line 41 to :dash chamber I1.

In another alternative all or a portion of the lighter fraction ofinsufficiently converted oil may be passed through line 54, valve 55,pump 55, valve 5I, valve 62 and line 24 through previously describedroutes to the catalytic cracking stes. At the same time a heavy fractionof the insuii'.- ciently converted oil may be withdrawn through line38,' line 40, valve 4I, line 42,'valve 43, pump 44, valve 45, valve 46,and line 41 to dash cham- .insufficiently converted oil to thenon-catalytic cracking step. The use of the intermediate iractions ofinsumciently converted oil as recycle stock in the manners describedabove is an importantfeature of the process since the life of thecatalyst mass and the extent of conversion can be regulated in anydesired mannerv depending upon the products desired and the charginstocks used. i

The optimum temperature range for catalytically cracking the hydrocarbonvapors is within the range of approximately W-120,0 F., and pressuresare suitably atmospheric or only slightly approximately pounds persquare inch.

Numeroustypes of 1cracking catalysts may be used, among which areiullers earth or other clays which have been treated with acids or otherchemicals, which have been promoted by the addition of metals or metaloxides. Another type of catalyst which may be usedto advantage comprisesrefractory oxides such as those of aluminum or magnesium which have beenpromoted by the addition of small percentages of metal oxidesincludingthose of chromium, molybdenum, vanadium, tungsten, iron, etc.One type oi' catalyst which has been particularly useful comprises acomposite oi a maior portion of precipitated silica having added theretoalumina and/or zirconia. These catalysts are prepared by mixing theprecipitated and washed hydrogels or coprecipitating the masses underconditions whereby alkali-metal compounds are substantially eliminated.'I'he masses are then formed into shapes by compression or extrusionmethods. dried. and calcined at temperatures in excess of 800 F. priorto their use inthe process. The ratio of the added compound to silicamay vary over' a considerable range and is normally within the limits ofapproximately 5-30% by weight.

The following example is given for purposes of illustration but shouldnot be interpreted as limiting the process tothe'exact conditions giventherein. l

A v26" A. P. was charged to the fractionating column 5 and theunvaporined portion was passed through coil I5 and reaction chamber I4where it was cracked at a temperature of' 9M F. vanda pressure of400poundspersquareinch. Thereactionprod- 'I. Midcontinent topped crudeoil I 'ucts were passed to ash chamber I1 from which a residual fuel oilhaving a Furol viscosity of 500 seconds at 122,n F. was withdrawn. Thevaporized products were passed to reaction 'chamber 5 and the gasolineand gaseous products were taken overhead. An intermediate boilingfraction of approximately 35 gravity was withdrawn from fractionator andpassed through coil 28 wherein it was vaporized and heated to thecracking temperature. The vapors were passed through catalytic converter32 where they contacted a precipitated silica-12% alumina- 'catalystmass at a temperature of 9 5 F. 'Ihe reaction products were passed tofractionator'35 from which the gasoline and gas were removed. The heavyrecycle oil was withdrawn through line 38 and line 4|!` and, asdescribed in the foregoing specifications, returned to flash chamber Il.An

intermediate boiling fraction of insufciently converted oil waswithdrawn through line 54, and

returned by previously described routes to the catalyticconversion step32 for further conversion to gasoline and gas. A total yield cfapproximately 59% of gasoline was obtained in this manner. Thecatalytically cracked fraction had an octane number v of 8l and thethermally cracked portion had an octane number of 72, the. l ,totaloctane number of the blend of material being 76. The yield of 76 octanenumber-gasoline-obtainable from this stock by non-catalytic crackingalone was approximately 51%.'

I claim as my invention:

vaporizing zone, separating a residual fraction unsuitable for furtherconversion, passing the vaporized portion of the reaction products tothe primary fractionation step, separating the gas, gasoline and anintermediatehboiling fraction, contacting .the last-named fraction invaporous form with a crackingcatalyst in a catalytic crackzirconia intosubstantial yields of relatively high anti-` l. A process for convertingVa hydrocarbon oil into vsubstantial yields of relatively high antiknockgasoline which comprises charging said oil to a primary fractionationstep and therein vaporizing a substantial portion of the oil, separatinga relatively heavyunvaporized fraction of the oil, subjecting saidfraction to non-catalytic cracking .in a heating coil and communicatingreaction chamber at a temperature and pressure adequate to eectsubstantial cracking thereof, passing the'reaction products into a-vaporizing zone at a reduced pressure, separating a residual fractionunsuitable for further conversion, passing the vaporized portion of thereaction products from said vaporizing zone to said primaryfractionation step, separating the gas, gasa line,- and anintermediate-boiling fracticn, contacting said intermediate fraction anddistillate fractions of the charging oil in vaporcus form with acracking catalyst in a catalytic cracking step under conditions adequateto eEect substantial cracking thereof, passing the reaction products toe, secondary fractionation step, recovering the gas and gasoline,separating the insunciently converted oil from said catalytic crackingstep into a low-boiling, an intermediate-boiling and a high-boilingfraction, mixing the high-boiling fraction with the low-boilingfraction, supplying the mixture to the aforesaid vaporizing zone of thenon-,catalytic cracking step, and' returning the intermediate-boilingfraction from said secondary fractionation step to said catalyticcracking step.

2. A process for converting a hydrocarbon oil into substantial yields ofrelatively high antiknock gasoline which comprises charging said oil toa primary fractionation step, separating a relatively heavy nnvaporizedAfraction of the oil, subjecting said heavy fraction to a noncatalyticcracking step in a heating coil and communicating reacting chamber at atemperature and pressure adequate to effect substantial crackingthereof, passing the reaction products into a ing step under conditionsadequate to eifect substantial cracking thereof, passing the reactionproducts to a secondary fractionation step, recovering the gas andgasoline',-separating the insumciently converted oil in said secondaryfractionation step into a lower-boiling fraction, anintermediate-boiling fraction, and a residual fraction, supplying saidlower-boiling fraction and a, portion of said residual fraction to saidAnon-catalytic cracking step, mixing said intermediate-boiling fractionof insufficiently con-1 verted oil with a portion of the residualfraction, and returning said mixture to said catalytic cracking step.

3. A process for converting a hydrocarbon oil knock gasoline whichcomprises charging said oil to a primary fractionation step and thereinvaporizing a substantial portion of the oil, separating a heavyunvaporized fraction of the oil, subjecting said fraction tonon-catalytic cracking in a heating coil and communicating reactionchamber at a temperature and pressure adequate to eect substantialcracking thereof, passing the reaction products into a vaporizing zoneat a reduced pressure, separating a residual fraction unsuitable forfurther conversion, passing the remaining portion of the reactionproducts to said primary fractionation step, separating gas, gasolineand an intermediate-boiling fraction, contacting said intermediatefraction and distillate fractions of the charging oil in vaporous formwith a cracking catalyst in a catalytic cracking step under conditionsadequate to effect substantial cracking thereof, passing the reactionprocl-v ucts to a secondary fractionation step, and separating the gasand gasoline from insuillciently converted oil, returning a relativelylight fraction of the insufliciently converted oil to said catalyticcracking step, and supplying a heavier fraction of said insumcientlyconverted oil to said primary fractionator. r

4. A process for converting a hydrocarbon oil into substantial yields ofrelatively high antiknock gasoline which comprises charging said oil toa primary fractionation step, separating a relatively heavy unvaporizedfraction of the oil,

subjecting said fraction to non-crfalytic cracking in a heating coil andcommunicating reaction chamber at a temperature and pressure adequate toeEect substantial cracking thereof, passing the reaction products into avaporizing zone `tuning fraction and a portion of the low-honingseparating gas,

said intermediate fraction of insuillciently converted oil and returningthe mixture to said catalytic cracking step, mixing a second portion ofthe low-boiling fraction and a second portion of the intermediateboilingfraction with the high-boiling fraction and returning the mixture to theaforesaid vaporizing zone.

5. A process for converting a hydrocarbon oil into substantial yields ofrelatively high antiknock gasoline which comprises charging said oil toaprimary fractionation step, separating a relatively heavy unvaporizedfraction of the oil, subjecting said fraction to non-catalytic crackingin a heating coil and communicating reactionV chamber at a temperatureand pressure adequate to eiect substantial cracking thereof, passing thereaction products into a vaporizing zone at a reduced pressure,separating a heavy residual fraction unsuitable for further conversion,passing the vaporized portion of the reaction products from saidvaporizing zone to the prlmary fractionation step, separating therefromthe gas,- gasoline, and an. intermediate-boiling fraction, contactingsaid intermediate fraction in vaporous form with a cracking catalyst ina catalytic cracking step under conditions adequate to effectsubstantial cracking thereof, pass- Y to the primary fractionation step.

4CHARLES L. THOMAS.

